Electric circuit breaker



May 9, 1939. E. B. MERRIAM ELECTRIC CIRCUIT BREAKER Filed Feb. 12, 1958 Inventor. Ezra B. Merriam,

by His Attorney Patented May 9, 1939 UNITED STATES PATENT OFFICE ELECTRIC CIRCUIT BREAKER New York Application February 12, 1938, Serial No. 190,262

7 Claims. (Cl. zoo- 59) My invention relates to electric circuit breakers of the fluid or oil blast type, and has for its principal object the provision of an improved and simplified explosion chamber oil blast circuit breaker.

In a well-known form of oil blast circuit breaker, a pair of breaks in series are formed within the explosion chamber upon opening of the circuit, the arc pressure generated at one of said breaks being utilized to cause an oil blast through the other break for interrupting the circuit. -T his form of breaker generallyincludes either an intermediate floating contact arrangement, or a conducting gate, .or the equivalent thereof, for separating the are into two sectionsior the purpose above described. Since this auxiliary structure necessarily complicates the explosion chamber construction and increases the cost of the construction and maintenance, it is highly desirable that the oil blast be produced as efiiciently as possible with a minimum of departure from the well-known single break explosion chamberbreaker wherein a movable rod contact coacts with a single fixed contact within the chamber.

In accordance with my invention the arc pressure itself is utilized to build up a momentary counter or back pressure to deflect the oil blast created by are pressure during the initial separation of the contacts so as substantially to traverse the arc path.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, Fig. 1 is an elevational sectional view of an oil blast circuit breaker embodying the present invention; and Fig. 2 is a similar view showing a modified form of bafiie structure.

Fig. 1 illustrates in general a well-known type of oil circuit breaker comprising a casing I containing an arc-extinguishing fluid such as oil, the level of which is indicated at 2*. It shall be understood that any suitable arc-extinguishing liquid, such as oil or water, for example, can be used, and that the term oil as used in the present specification and claims is intended to comprehend such a liquid.

The relatively movable contact structure which is separable within the breaker casing in the oil comprises in the present instance a fixed contact structure 3, which may be of any suitable type such as the segmental socket type shown, and a movable rod contact 4 coacting therewith. The rod contact 4 in the closed circuit position is in engagement with the fixed contact segments 3', and in the opening operation the rod contact is raised so that the are forms between the tip of the rod contact and the arcing ring 3" of the fixed contact.

For the purpose of utilizing for are interruption the pressure developed within the oil by the are, there is provided a cross-blast baiile 5 composed of a suitable mechanically strong insulating material and forming both a lo: gitudinal passage 6 for the rod contact and a substantially transverse passage 1 intersecting the longitudinal passage. The transverse passage I interconnects the high pressure chamber i in which the arc is initially formed, and a comparatively low pressure or exhaust region I" which is generally at atmospheric pressure.

In the arrangement so far described it will be apparent that when the rod contact 4 is within the longitudinal passage 6 so as also to close the transverse passage the arc presure in the chamber I necessarily builds up rapidly since all of the exhaust passages are closed. when, however, the contact tip 4 clears the transverse passagethere will take place a blast of oil through the passage 1 into the low pressure or exhaust chamber I".

Since it has been found that an oil blast transverse to the arc is in certain cases more eflective than a blast along the longitudinal axis thereof,

' it is highly desirable that the oil blast be confined to the passage 1 instead of through the longitudinal passage 6 when the rod contact has cleared the same. To this end the baflle structure 5 is provided with an extension 8 through which the longitudinal passage 6 also extends. The passage 6 at this part, that is, between the transverse passage 1 and the low pressure chamber, has formed therein auxiliary oil reservoirs or pockets that contain oil in closely spaced relation to the are path so that vaporization of the oil is facilitated. This 011 is for the purpose of insuring adequate arc counterpressure in the passage 6 for deflecting the oil blast through the transverse passage 1. In the present instance the oil reservoir or reservoirs is formed by annular grooves or recesses 9 disposed along the walls of the passage 6. It shall be understood of course that the passage walls can be defined by irregularities other than specifically illustrated for accomplishing the purpose in question.

In operation, when the rod contact 4 moves through the passage 8 to open the circuit, the arc, assuming that it is not extinguished during the first part of the opening stroke, vaporizes oil stored in the auxiliary reservoirs 9 so that a considerable gas pressure is built up within the upper part of the contact passage. When the rod contact 4 clears the passage 6 this are pressure, although now vented to a low pressure region, still maintains momentarily an appreciable counter-pressure in the upper part of the passage 6, as compared with a smooth bore that may be momentarily practically clear of oil at the instant of contact clearance. The irregular wall surface of the passage 6 above the trans-. verse passage also tends to retard immediate release of the counter-pressure.

This counter-pressure within the upper part i .of the passage 6 therefore deflects to a great extent the oil blast through the transverse passage 1 so that the arc is primarily subjected to a cross-blast instead of a longitudinal blast through the contact passage 6.

Fig. 2 illustrates a modification of the balile structure 5 wherein the auxiliary reservoir in the upper part of the contact passage 6 constitutes a single small explosion chamber In that functions generally in the manner above described to build up a momentary counter-pressure in the contact passage 6 that is sufiicient to deflect a strong cross-blast through the are by way of the passage 1.

In certain cases it may be advantageous to define the walls of the passage Ii by irregularities between the cross-blast passage I and the arc chamber I. In this event the passage 6 at that point would have sufficient length to permit a momentary counter-pressure with the result that the main oil blast is deflected through cross-passage 1. Such an arrangement is indicated in Fig. 2 at H.

It should be understood that my invention is not limited to specific details of constructionand arrangement thereof herein illustrated, andthat changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric circuit breaker comprising an explosion chamber containing oil, relatively movable contacts separable within said chamber, a baflie structure through which the arc is drawn by one of said contacts, said bafile structure forming also a passage extending substantially transversely of the arc path, said passage communicating with the region in which the arc is initially drawn and exhausting to a comparatively low pressure region, and means defining irregularities forming a substantially enclosed auxiliary oil reservoir closely adjacent that part of the arc path at one side of said transverse passage and arranged so that the arc builds up counterpressure in said part of the arc path after contact clearance for deflecting the oil blast through said transverse passage and directly across the are.

2. An electric circuit breaker comprising an explosion chamber containing oil, relatively movable contacts separable within said chamber, and baffle structure through which the arc is drawn upon separation of said contacts, said baille structure forming a longitudinal contact passage and an intersecting substantially transverse passage communicating with the region in which the arc is first drawn and exhausting to a comparatively low pressure region, said longitudinal passage having formed in the sides thereof between said transverse passage and low pressure region pockets defining an auxiliary oil reservoir arranged so that counter-pressure is built up by the are after contact clearance for deflecting the oil blast through said transverse passage.

3. An electric circuit breaker comprising an explosion chamber containing oil, a fixed and a coacting rod contact separable within said oil, and

bailie structure through which said rod contact is operable, said baflie structure forming a passage substantially transverse to the path of said rod contact, said passage communicating with the region in which the arc is initially drawn and exhausting to a comparatively low pressure region, said baflie also forming annular oil reservoirs closely adjacent and surrounding said contact path at a point between said transverse passage and said low pressure region so that the arc at said point builds up a counter-pressure after clearance by said rod contact for deflecting the oil blast through said transverse passage.

4. An electric circuit breaker comprising an explosion chamber containing oil, a fixed and a coacting rod contact separable within said oil, and battle structure through which said rod contact is operable, said baffle structure forming a passage substantially transverse to the path of said rod contact, said passage communicating with the region in which the arc is initially drawn and exhausting to a comparatively low pressure region, said bafile also forming an auxiliary comparatively small substantially enclosed explosion chamber along said contact path at a point between said transverse passage and said low pressure region arranged so that the arc builds up a counter-pressure in said auxiliary chamber after clearance by said rod contact for deflecting the oil blast through the said transverse passage.

5. An electric circuit breaker comprising an explosion chamber containing oil, relatively movable contacts separable within said chamber, a baflle structure through which the arc is drawn upon separation of said contacts, said bafile structure forming an exhaust passage extending substantially transversely of the arc path, and means defining irregularities along said are path closely adjacent the arc at one side of said transverse passage arranged so that the arc builds up a momentary counter-pressure in said part of the arc path after contact clearance for deflecting the oil blast through said transverse passage and directly across the arc.

6. An electric circuit breaker comprising an explosion chamber containing oil, relatively movable contacts separable within said chamber, a baflie structure through which the arc is drawn upon separation of said contacts, said baflle structure forming an exhaust passage extending substantially transversely of the arc path, and means defining irregularities along said are path and closely adjacent said are at opposite sides of said transverse passage arranged so that the arc builds up momentarily counter-pressures at opposite sides of said passage after contact clearance for deflecting the oil blast through said passage and directly across the are.

7. An electric circuit breaker of the fluid blast type comprising an arc chamber in which relatively movable contacts separate upon opening of the circuit, an insulating baffle structure forming a partition in said chamber and defining a passage through which the arc is drawn by said separating contacts, said bafile structure also forming another passage communicating with both parts of said are chamber so as to exhaust across said arc, said first-named passage also forming a reservoir for said fluid for causing an arc counter-pressure in said passage after contact clearance tending to deflect an arc-extinguishing blast of fluid from that part of said arc chamber in which the arc is initially formed through said second-named passage.

. EZRA B. MERRIAM. 

